Former finance minister George Bonello Dupuis finds the recent behaviour of disgruntled Nationalists "sickening" and thinks backbencher Franco Debono has ruined his career with his parliamentary antics.

Dr Bonello Dupuis told The Sunday Times he wanted to help the Prime Minister in a time of need, and teach a lesson to hot-headed Nationalists who "grouse" over losing their posts.

He said Dr Debono - who missed two votes in Parliament and underlined the government's delicate majority - would never be trusted again.

"Who knows what he will be up to next time? He was silly to do what he did. It's simply not done to run away from a vote in Parliament, particularly when it's a vote which concerns you."

He believes Dr Debono should be strongly disciplined.

"Who does he think he is? He is not there because he is popular, but because the party put him on its ticket."

He also lashed out at outgoing EU commissioner Joe Borg, who expressed his frustration after learning about his replacement from the evening news.

Dr Bonello Dupuis argued that any appointee was there "for the duration of the Prime Minister's pleasure".

People like Dr Borg should retire gracefully and not "give fodder to the enemy".

"Unfortunately, people do not have enough gumption to say their snout has been in the trough for quite a while. Rather than thank their lucky stars that they have been appointed, they grouse when they are replaced by others," he said.

Dr Bonello Dupuis, 82, was in politics for 25 years, most prominently when former Prime Minister Eddie Fenech Adami appointed him finance minister for nine years.

The successful notary, who was also president of Sliema Wanderers, was then let go by the Prime Minister, causing him great disappointment, which he "took on the chin".

"When Eddie told me he had had enough of me, I retired gracefully. I was disappointed, because it was just two days after my biggest triumph (selling off the Bank of Valletta shares) but you have to take it like a man," he explains proudly.

"I always said you should not put someone in Cabinet if they haven't ever been in football, because in football you are 11 and if you're not good, you leave. What if I don't let one of my players out on the field? Will he go complain to Floriana?"

He thinks it is fine to criticise one's own party, but only if it is done internally, and within the party's structures, not in public.

"You don't give joy to the opposition. You keep your gunpowder dry to shoot at the enemy not wet so you can't shoot."

He advised the Prime Minister to "take more care in breaking the news" and to "sugar the pill" because he is dealing with human nature.

However, nothing justified going public with one's gripes - especially at a time of economic crisis which puts the Prime Minister in a vulnerable position.

Dr Bonello Dupuis recalls the letter he wrote to Dr Fenech Adami when he was removed from his post during a Cabinet reshuffle. He said he did not hold it against the Prime Minister at the time - on the contrary, he wrote to tell him he believed the team was supreme.

In response, then Prime Minister said he was overwhelmed by Dr Bonello Dupuis' reaction but had no doubt he would accept the decision as the perfect gentleman he was.

Dr Fenech Adami wrote back: "I have learned a lot from you over the years, particularly about the importance of team spirit, but I shall never forget the lesson you gave me today."

Speaking about the letters he treasures to this day, Dr Bonello Dupuis says: "That's the way things should be done."

He adds that in his time, the only person who behaved like today's disgruntled Nationalists was Josie Muscat.

"But we kicked him out, even though he was a kingpin in Żabbar. He thought he was greater than the party. But no one is; no one deserves to be."